Thanks everyone, I've read lots of conficting reviews about them - they're either all or nothing.
Poor lad's problem is his belly, he bites it raw then it gets infected and painful. Apparently he's been tried on everything - creams, pills, alternative remedies - but nothing helps. He's loads better since he's been wearing the cone but it just looks so uncomfortable and awkward. I think they're fine for a week or two but not months on end.